1

1. In a small-scale trial(sample size=9)of a psychotherapy treatment for depression,participants were assessed with a depression scale when they entered the trial and again when they have completed the6-month trial.The data yieldedamean difference (change) scoreof1.5and the standard deviation of the sampling distribution was.6.What was the thetstatistic?
2. .17
3. 2.5
4. 1.5
5. .5

1 points

QUESTION 2

1. A sample with 4data pointswas used to estimate the population standard deviation, which turns out to be .83.What is the standard deviation of the sampling distribution (or called standard error)?
2. .83
3. 1.66
4. .42
5. .21

1 points

QUESTION 3

1. To see if the amount of sleep differs between summer and winter,a researcher asks a group of 30subjects to record their sleep duration everyday for the whole month ofJuly and the whole month of January.The researcher then calculate an average summer sleep time and an average winter sleep time for each subject. What is the degree of freedom for obtaining the criticaltvalue from thettable?
2. 59
3. 28
4. 58
5. 29

1 points

QUESTION 4

1. Which statement is true about the estimated standard deviation of the population?
2. The estimated population standard deviation can be either larger or smaller than the calculated sample standard deviation, depending on the samples size.
3. The estimated population standard deviation is smaller than the sample standard deviation.
4. The estimated population standard deviation is larger than the sample standard deviation.
5. The estimated population standard deviation is the same as the sample standard deviation.

1 points

QUESTION 5

1. A researcher tested a research hypothesis that people with diagnosed depression will have REDUCED level of depressive symptoms after a cognitive therapy treatment, as compared to the pre-treatment level of depressive symptoms. The cutofftvalue is -1.833 for this one-tailed test. The data analysis yielded a mean change score (post-treatment minus pre-treatment) of -2.5. If the standard error is 2.0, what is thetstatistic and what is the conclusion of the hypothesis test?
2. -2.5;reject the null hypothesis
3. -1.25;fail to reject the null hypothesis
4. -2.5;fail to reject the null hypothesis
5. -1.25;reject the null hypothesis

1 points

QUESTION 6

1. According to a recent report, the average American takes 10 days of paid vacation per year (but the standard deviation is unknown). An employer wonders if this trend exist in her company as well, so she collected data of vacation days taken during the past year from a randomly drawn sample of 50 employees in her company. What would be the appropriate test to see if her employees' take significantly more or significantly fewer vacation days compared to the national average?
2. Paired-samplesttest
3. Z test
4. Independent-samplesttest
5. One-samplettest

1 points

QUESTION 7

1. A researcher set up a directional null hypothesis for attest,with an alpha level of .01 and dfof 15.What is the criticaltvalue from thettable?
2. 2.947
3. 2.132
4. 1.753
5. 2.603

1 points

QUESTION 8

1. In which condition is at-test used instead of aZ-test?
2. When the population standard deviation is unknown.
3. When the population is normally distributed.
4. When there is only one sample.
5. When the sample size is smaller than30.

1 points

QUESTION 9

1. You conduct attest for paired samples (dependent means)and fail toreject the null hypothesis.This should lead to the conclusion that ____.
2. there is no significant difference between the two populations represented by the two sets of scores
3. thepopulation represented by the sample is not significantly different from the general population
4. thepopulation represented by the sample is significantly different from the general population
5. there is a significant difference between the two populations represented by the two sets of scores

1 points

QUESTION 10

1. In a math class,students take a pre-test at the beginning of a new module and then a post-test after the module. The instructor plans to compare the pre-test and post-test scores of the students to see if they score significantlyhigher at the end of the semester. He can conduct a one-samplettest for this comparison after ______.
2. calculating the mean of the pre-test scores and the mean of the post-test scores
3. calculating each student's "change" (difference)score
4. estimating the standard deviation for the pre-test scores and the standard deviation for the post-test scores
5. obtaining a national mean score on the same test

1 points

QUESTION 11

1. A researcher found a strong positive correlation betweenvariable X and variable Y, what is the direction of causality between these two variables?
2. X causes Y
3. Y causes X
4. A third variable causes both X and Y
5. All of the abovechoices here are possible

1 points

QUESTION 12

1. Which of the following meets the APA standardsfor reporting the hypothesis test result of correlation as performed by SPSS?
2. r(.52)=.01
3. r=.52,p=.03
4. p(r=.52)=.03
5. r =.52,p<.05

1 points

QUESTION 13

1. In a study,SAT math score was found to be correlated with college freshman math grade withr=.6,p=.15.The proportion of variance in freshman math grade that is shared withthe variance in SAT math score is ___.
2. 2.25%
3. 60%
4. 15%
5. 36%

1 points

QUESTION 14

1. Which of the following is not part of the calculation processof correlation coefficient?
2. Adding the multiplication results from the linked Z scores
3. Converting original scores into Z scores
4. Multiply the linked Z scores from the two variable
5. Dividing the sum of the Z score multiplications by the standard error

1 points

QUESTION 15

1. For converting data points into Z scores in the computation of Pearson correlation coefficient,the denominator of the Z score formula is _____.
2. standard error
3. estimated standard deviation of the population
4. the standard deviation within the sample
5. estimated standard deviation of the sampling distribution

1 points

QUESTION 16

1. When examining the correlation analysis result from a statistical program, what information determines whether there is a significant correlation or not?
2. r²
3. r
4. df
5. p

1 points

QUESTION 17

1. Which of the follow-up studies can shed light on a possible causal relationship after a significant correlation between two variables has been demonstrated?
2. A survey study to ask subjects for a cause for the observed data
3. A longitudinal study to monitor the two variables
4. A between-subjects study to measure the two variables in different samples
5. A cross-sectional study to compared groups that vary on the two variables

1 points

QUESTION 18

1. Two studies were conducted to examine the number of hours per week spent in Blackboard andthe final grade in a course. The significance (alpha) level was set to be .05 in both studies. Study 1 obtained a result ofr= .40,p =.08;Study 2 yielded a result ofr=.35,p=.04.Which of the following is an accurate comparison between the two studies?
2. Study 2showed a larger effect size than study 1.
3. Study 2 showed a significant correlation but study 1 did not.
4. Study 1showed a significant correlationbut study 2did not.
5. Both studies show a significant correlation of medium strength

1 points

QUESTION 19

1. Four students reported their study time and test score from a statistics course and their data have been converted into Z scores in the table below. What is Pearson's correlation coefficient from this data set?
3. -.67
4. .25
5. -.50
6. -2

1 points

QUESTION 20

1. You are interested in the relation between the number of years working for a particular company and job satisfaction. You survey 40 workers at this company and obtain a correlation coefficient of .30between these two variables. What is the effect size of this correlation?
2. .40
3. .30
4. .09
5. .05

1 points

QUESTION 21

1. Elementary school A has implemented an after-school sports program and the principle would like to know if the participants of the sports program are becoming more active in general, compared to students who are not participating in the program. So the principle collected data on overall physical activities throughout the week from a group of the sports program participants and a group of school A students not in the program. The most appropriate statistical test for data analysis would be ___.
2. Independent-samplesttest
3. Pearson's correlation
4. Paired-samplesttest
5. One-samplettest

1 points

QUESTION 22

1. A researcher wants to examine the effectiveness of a new reading program for students with poor reading skills.She recruits 100 students in eighth grade with poor reading skills for the study. Half the subjects participate in the new reading program while the other half of the subjects participate in the regular reading program. After a semester, all 100 students are assessed for their reading skills to determine whether the new reading program works better than the regular reading program. To which population does the researcher hope to generalize the finding?
2. All eighth-grade students with proficient reading skills.
3. All eight-gradestudents with poor reading skills.
4. All student who have participated in the new reading program.
5. All students who are learning to read.

1 points

QUESTION 23

1. The comparison distribution for attest for independent means (independent-samplesttest)is _____.
2. adistribution of differences between means
3. adistribution of difference scores
4. a distribution of the general populationscores
5. adistribution ofsample means

1 points

QUESTION 24

1. When you conduct attest for independent means,____.
2. you reject the null hypothesis if thetscore is more extreme than the cutoff(criterion)tscore
3. you need to make sure that the two sample sizes are exactly the same
4. you should only use an alpha level of .01 because of the lower power of this test compared to dependent-meansttest
5. you need to make sure that the medians of the two populations are equal

1 points

QUESTION 25

1. Paired-samplesttestand independent-samplesttest share which of the following characteristics?
2. The degree of freedom is calculated as (N₁-1)+(N₂-1)
3. A pooled variancefor the populations needs to be calculated in the process.
4. The number of scores in one set of data points is the same as that of the other set of data points.
5. The comparison distribution has a mean of zero.

1 points

QUESTION 26

1. Consider a study in which the population variance estimate based on an experimental group of 10 participants is 6 and the population variance estimate based on a control group of 20 participants is 3. Compute the pooled estimate of population variance.
2. 5
3. 3
4. 4
5. 2.5

1 points

QUESTION 27

1. Whenconductingattest for independent means, a typical alternative hypothesis might be ________.
2. the mean of the population of interest is significantly different from the mean of the general population
3. the mean of sample1is different from the mean of the general population
4. the mean of population1is significantly different fromthe mean of population2
5. the mean of the population ofchange scoresis significantly different from 0

1 points

QUESTION 28

1. Calculate the effect size for an independent-samplesttest,based on the following information:
2. Group 1 has 10 subjects and the sample mean is 23.
3. Group 2 has 10 subjects and the sample mean is 11.
4. The pooled variance for the populations is 25.
5. 1.27
6. .08
7. .58
8. 2.4

1 points

QUESTION 29

1. Which of the following is an accurate statement about the independent-samplesttest?
2. The scores in the two samples are paired up to calculate difference scores.
3. The two sample means are separately compared to two sampling distributions.
4. The two sample sizes can be different.
5. The two samples are combined into one sample to estimate the pooled variance for the populations.

1 points

QUESTION 30

1. The comparison distribution for an independent-samples (independent-means) t test consists of _____.
2. difference scores
3. sample means
4. mean differences
5. original scores from the two populations from which the two samples are drawn

1 points

QUESTION 31

1. A researcher concludes his study by stating that "a chi-square test for independence indicated that males and females differ significantly in their preferred coffee drink[²(5, N = 100) = 21.66, p = .025]." What is the chi-square value in this study?
2. .025
3. 21.66
4. 100
5. 5

1 points

QUESTION 32

1. A randomly-drawn largesample that comes from a normally distributed population:
2. is always skewed either to the left or to the right
3. always has a smaller mean than that of the population
4. is often approximately normally distributed
5. might have a smaller variance than that of the population

1 points

QUESTION 33

1. The formula for the chi-squared statistic is ______.
2. [(O-E)²]/F
3. [(O-E)²/E]
4. O/[(O-E)²]
5. E/[(O-E)²]

1 points

QUESTION 34

1. A situation of no relation between variables in a contingency table is known as _____.
2. independence
3. dependence
4. negative correlation
5. goodness of fit

1 points

QUESTION 35

1. A Chi-square test for independence is conducted to see if pet preference (cat or dog)differs between men and women.What is the null hypothesis?
2. Pet preferencedoes not differ by gender.
3. The number of people preferring a dog is the same the number of people preferring a cat for a pet.
4. Pet preferencedepends ongender.
5. There is a relationship between pet preferenceand gender.

1 points

QUESTION 36

1. "(N_Columns-1) (N_Rows-1)" is the formula for the degrees of freedom for:
2. the chi-square test for independence
3. bivariate correlation
4. independent-samples t test
5. the chi-square test for goodness of fit

1 points

QUESTION 37

1. A Chi-square testfor goodness of fit is conducted with 100individualsto see if chocolate and vanilla ice cream are equally popular.Below is the table for calculation.What is the X²statistic?
2. Ice cream flavor
3. OF
4. EF
5. OF-EF
6. (OF-EF)²
7. (OF-EF)²/EF
8. Chocolate
9. 75
10. 50
11. 25
12. 625
13. 12.5
14. Vanilla
15. 25
16. 50
17. -25
18. 625
19. 12.5
20. 25
21. 12.5
22. 50
23. 625

1 points

QUESTION 38

1. The extent of mismatch between observed frequency and expected frequency of a situation is calculated as the ___statistic.
2. Z
3. t
4. X²
5. F

1 points

QUESTION 39

1. A Chi-square test for goodness of fit is conducted to see if the three major news sources, TV news,onlinenews, and printed newspapers, are equally utilized among college students. A randomly selected group of 100 students were asked to select the most frequently used news source from the three choices. The X²is calculated to beto be 7.87, what is the hypothesis test conclusion if the alpha level has been set at .05?
2. Fail to reject the null hypothesis because theX²statistic is less extreme than the critical X²value.
3. Fail to reject the null hypothesisbecause theX²statistic is more extreme than the critical X²value.
4. Reject the null hypothesis because theX²statistic is less extreme than the critical X²value.
5. Reject the null hypothesis because the X²statistic is more extreme than the critical X²value.

1 points

QUESTION 40

1. Which step below is not part of the calculation of Chi-square statistic?
2. divide each squared difference between observed and expected frequencies by the expected frequency for its category or cell
3. determine the expected frequencies in each category or cell
4. determine the actual, observed frequencies in each category or cell
5. figure the overallFratio by figuring, for each category or cell, the observed minus expected, and squaring this difference